Interference pattern with some fringes missing

[russel.arnold]

hi

i was wondering whether we can produce a interferece pattern with some bright fringes missing( i.e not appearing at all). If yes..how it can be achieved?

 

[russel.arnold]

also i want that the intensity of the remaining bright fringes should be same

 

[Andy Resnick]

Sure- that's an active field of engineering- creating a specific far-field diffraction pattern.

Since the far-field pattern is the Fourier transform of the exit pupil, what is done (in principle) is to start with the desired pattern (in this case, say sin(x)*(1-rect(x)) which is a sine wave with the central fringe missing), and perform an inverse Fourier transform.

In practice, this is tricky since (1) there are zeroes in the function and (2) the transforms have to be complex (phase-only gratings), and (3) manufacturing currently produces diffracting objects with discrete levels of phase retardation.

There was a company in Huntsville, AL that does this (but maybe not your specific application):

http://jenoptik-inc.com/microoptic-solutions/diffractive-optical-elements.html

 

[russel.arnold]

@ andy sir

thanks for the reply..

well basically my problem is to create a 1 D photonic structure using optical induction (in a photorefractive material). Since it is sensitive to light, we will create the interfernce pattern using 2 beams which || give rise to 1D spatially varying periodic refractive index structure. Now nxt step is to break this periodicity. So..we must have atleast one missing fringe in the corresponding pattern.

Can u suggest some more possibe ways to carry out this??